1. Field of the Invention
The present invention relates to a method and apparatus for detecting airborne articles, and more particularly, for responding to detection of smoke from an electronic enclosure.
2. Description of Related Art
An electronic system, such as a computer system, is conventionally comprised of various electronic devices or components, including peripheral devices such as disk drives, that are mounted and electrically interconnected within one or more electronic enclosures or cabinets. In many applications, such as commercial business operations, each of the electronic enclosures for the system is installed in a room of a building or other structure that provides a controlled environment for system operation. Since electronic systems can dissipate a large amount of heat, ventilation is generally provided for removing the heat from both the cabinets and the room to avoid creating a high temperature condition that could result in a system failure.
Electronic devices, if allowed to overheat, are susceptible to malfunctions or permanent damage. In more extreme situations, an overheated device could potentially initiate a fire within an enclosure that, unless detected and suppressed, could cause extensive damage, not only to the particular enclosure, but also to nearby enclosures and possibly to the room. An overheated device may be caused by various factors, such as inadequate cooling, electrical short circuits or the like.
One scheme for detecting a potential fire event associated with an electronic system involves the placement of one or more smoke detectors within the ventilation system of the room. Air drawn from the room through the ventilation system is monitored by the smoke detector. When an unacceptable amount of smoke is detected, the smoke detector typically generates an alarm signal that may be either presented to a human operator for investigation and response or used to automatically terminate electrical power to the entire room. In some instances, a fire suppressant may be automatically discharged into the room.
Applicants have recognized that such a detection scheme suffers from several drawbacks. For example, this scheme lacks an ability to isolate and shut down only the particular source of a smoke event. Rather, electrical power is typically interrupted for the entire room, thereby shutting down each system or subsystem of equipment housed within the room until the source of the smoke event can be identified and rectified. Such action is undesirable to an enterprise, such as a bank, a telephone company or an airline, which relies upon continuous access to its computer and data storage systems.
A room monitoring scheme may also experience delay in detecting a smoke event which could potentially result in more extensive damage as the length of the delay increases. This could lead to damage not only to the equipment that is the source of the smoke, but also to surrounding equipment should the event lead to a spreading fire. Depending on the particular room configuration, the smoke detector may be located a significant distance away from the source of the smoke, thereby increasing the amount of time that the event could be allowed to continue before its detection. Additionally, the dilution of smoke particles within the ventilation air for the entire room may lower the concentration of particles in the air monitored by the detector which could also delay the detection of a smoke event.
It is an object of the present invention to provide an improved method and apparatus for detecting and responding to the presence of airborne particles, such as smoke, generated within an electronic enclosure.